Granulomatous and fibrotic pulmonary diseases in man and animals are being characterized by examining alveolar exchange, hemodynamics of the pulmonary and bronchial circulations, the response of particular cell types to the presence of granulomas, the in vivo and in vitro metabolism of pulmonary tissues, the behavior of the respiratory muscles, the biochemistry and immunochemistry of the lung and its vessels, and the regulation of intrapulmonary enzymes.